Self-cleaning wearing ring for centrifugal pump pumping mixture of liquid and solid



July 7, 1964 H. M. POLLAK 3, 3

SELF-CLEANING WEARING RING FOR CENTRIFUGAL PUMP PUMPING MIXTURE OF LIQUID AND SOLID Filed Aug. 28, 1962 s Sheets-Sheet 1 FIG.

INVENTOR HENRY M. POLLAK HIS ATTORNEY 3,139,831 UMP July 7, 1964 H. M. POLLAK SELF-CLEANING WEARING RING FOR CENTRIFUGAL P PUMPING MIXTURE OF LIQUID AND SOLID 3 Sheets-Sheet 2 Filed Aug. 28, 1962 FIG. 3

FIG. 2

INVENTOR HENRY M. POLLAK HIS ATTORNEY July 7, 1964 H. M. POLLAK 3,139,831

SELF-CLEANING WEARING RING FOR CENTRIFUGAL PUMP PUMPING MIXTURE OF LIQUID AND SOLID Filed Aug. 28, 1962 3 Sheets-Sheet 3 INVENTOR v HENRY M. POLL/4K FIG. 4 BY v ms ATTORNEY United States Patent Henry M. Foiialr, New York, N.Y., assignor to Ingersoll- Rand Company, New York, N.Y., a corporation of New Jersey Filed Aug. 28, 1962, Ser. No. 219,991 1 Claim. (Cl. 103-103) The present invention relates to centrifugal pumps and more particularly to a Wearing ring for such apparatus.

Heretofore, it has been known that when a mixture of solids immersed in a liquid was pumped by a centrifugal pump fitted with a standard wearing ring having a standard horizontal ring fit between the wearing ring and the impeller of the pump, some of the solid particles would find their Way, and become lodged, in such horizontal ring fit. When a sufficient number of particles. accumulate to form a large mass they act as a wedge and bind the pump (i.e. impair or stop the rotation of the pump impeller).

There have been several attempts to solve this problem as taught, for example, by U.S. Patent No. 2,890,660 issued June 16, 1959 to E. Umbricht which employs sharp edge cooperating with impeller blades to chew up the lumps, and auxiliary blades chewing up any solid material between the top of the impeller disc and cover. This is not only a complex and costly design but it also greatly reduces the efficiency of the pump.

U.S. Patent No. 2,835,203 issued on May 20, 1958 to R.Cliborn teaches the employment of a recess in the back of the pump impeller which acts as a pumping groove to evacuate the chamber. Basically this method does not provide a means for cutting up the particles and is of questionable value where entrenched particles bind and cause malfunction of the pump.

It is the general object of the present invention to avoid and overcome the foregoing and other difliculties of and objections to prior art practices by the provision of a wearing ring that will resist clogging and eliminate the binding of the centrifugal pump While pumping a mixture of solid material immersed in a liquid.

Another object of the present invention is to provide for the cutting and/ or shredding of a solid that might be lodged on the wearing ring surface.

Still another object of the present invention is to provide a means for clearing the solid from the wearing ring surface.

Yet another object of the present invention is to allow the use of close clearances between a stationary and a moving surface under certain conditions (cg. when pumping a mixture of solids immersed in a liquid, at relatively high speeds), where formerly close clearances could not be maintained, and thus reduce leakage adjustment and increase pumping efliciency.

A further object of the present invention is to make the invention adaptable to any pump designed for use with a conventional wearing ring.

The aforesaid objects of the present invention, and other objects which will become apparent as the description proceeds, are achieved by providing a nonclogging centrifugal pump, for pumping a fluid mixture of solids immersed in a liquid and having a suction side. Such improved centrifugal pump has a pump casing, and a rotating moving means disposed within the pump casing for pumping the fluid. A stationary means is fitted on the pump casing and is operatively associated with the rotating moving means for maintaining minimum clearance with respect to the rotating moving means. A particle receiving means, and a cutting and shredding means, are both disposed on the stationary means for receiving, controlling and (com- 3,139,831 Patented July 7, 1964 bining with the rotating moving means) to cut up the accumulated particles. The cutting and shredding means are provided with a guiding means for guiding the cut particles to the suction side and for dispersing the cut particles.

For a better understanding of the present invention reference should be had to the accompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIGURE 1 is a fragmentary vertical sectional view of a centrifugal pump showing the special vertical wearing ring and its location with respect to the centrifugal pump casing and the pump impeller and,

FIGURE 2 is an enlarged perspective view along the line 22 of FIGURE 1 in the direction of the arrows and showing the clearing slots.

FIGURE 3 is an enlarged perspective view along the line 22 of FIGURE 1 in the direction of the arrow and showing curved clearing slots.

FIGURE 4 is a fragmentary vertical sectional view of the stuffing box assembly of a centrifugal pump, showing the throat of the stufling box with respect to the pump impeller.

FIGURE 5 is an enlarged perspective view along the line 5-5 of FIGURE 4 in the direction of the arrows and showing the clearing slots.

Although the principles of the present invention are broadly applicable to any two parts of a centrifugal pump where one part is stationary and the other is rotating and where close clearance is required, the present invention is particularly adapted for use in conjunction with the wearing ring and the impeller of a centrifugal pump, and hence it has been so illustrated and will be so described.

With specific reference to the form of the present invention illustrated in the drawings, and referring particularly to FIGURE 1, a centrifugal pump is indicated gen erally by the reference numeral 10. This centrifugal pump 10 has a suction side, comprising a pump casing 11, a rotating moving means, such as the pump impeller 12, disposed within said pump casing 11, for the purpose of pumping a fluid mixture of solids (such as metal chips) immersed in a liquid, such as lubricating oil. The impeller 12 is provided with a front shroud 31 and a rear shroud 33 to aid in the pumping of the fluid mixture. A stationary means, such as a special vertical ring fit wearing ring 18, is disposed on said pump casing 11, and is operatively associated with the pump impeller 12 for maintaining minimum vertical ring fit clearance with respect to the pump impeller 12, thereby decreasing fluid leakage and increasing pump output and pump efficiency. It can be seen that when the clearance 20 between the front surface 19 of the wearing ring 18 and the front shroud surface 21 of the front shroud 31 of the pump impeller 12 is reduced, the leakage will be reduced thus increasing the pumping efficiency of the centrifugal pump. However, it can also be readily seen that as the clearance 20 is reduced, it increases the possibility of particles accumulating in the clearance 20, becoming lodged therein, and affecting a condition which will cause the centrifugal pump 10 to bind.

To provide means for avoiding the binding effect a particle receiving means, such as clearing slots 22, FIG- URE 2, are disposed on the wearing ring 18, to collect the particles; a cutting and shearing means, such as the shearing edges 24 of the clearing slots 22 for cutting up the accumulated particles are provided on the clearing slots 22; and a guiding means, such as combined and cooperative action of clearing slots 22 and the rotation of the pump impeller 12 (for guiding the particles to the suction side of the pump and dispersing them) is provided. Thus it becomes obvious that no particle accumulation of suflicient size, to cause the centrifugal pump to bind,

will develop, notwithstanding the minimizing of the clearance 20.

Operation Even though his believed the operation of the apparatus will be apparent from the foregoing description, a brief review of such operation will now be made for purposes of summary and simplification. Particularly as shown in FIGURE 1, the special wearing ring 18, is installed so that the clearance 20 between the special wearing ring 18 and the pump impeller 12, is in a vertical position at the base of a cavity 30, formed by the centrifugal pump casing 11, the wearing ring 18 and the pump impeller 12. As the pump impeller 12 rotates thus pumping the mixture of solid particles immersed in liquid, some particles will work their way downwardly through the cavity 30, down into a collecting pocket 30a comprising the front shroud 31 of the impeller 12 and the wearing ring 18 as shown in FIG. 1, and will go into the clearance 20 and will be picked up by the clearing slots 22. As a number of particles accumulate and build up to form a potentially obstructive mass, the shearing action, between the pump impeller 12 and the shearing edges 24 of the clearing slots 22, cuts up the mass of particles and thus prevents the accumulation of a mass of sufiicient size so as to interfere with the rotation of the pump impeller 12 and thus bind the pump. The chopped or sheared particles are guided by the clearing slots 22 either to the outside or to the inside (of the pump suction side) of the wearing ring 18, depending upon the rotation of the pump impeller 12, and are there dispersed therefrom.

It will be understood by those skilled in the art that alternatively the principles of the present invention may be practiced where close clearance is desired between two parts, one stationary and one rotating moving, such as between the throat 34 of a stufiing box assembly 32 and the pump impeller 12 of a centrifugal pump.

It will also be understood by those skilled in the art that alternatively the clearing slots 22 can be located on the rotating moving face of the pump impeller 12 or on both faces of the wearing ring 18 and pump impeller 12 respectively. The clearing slots 22 can be straight and randomly angularly disposed to provide longer shearing edges or curved and their design, e.g. width, depth, shape, etc., is determined by the characteristics of the liquid mixture, and the required leakage tolerated between the stationary and the rotating parts.

It will be recognized by those skilled in the art that the objects of the present invention have been achieved by providing a means to receive, cut up and clear accumu- 4 lated large particle masses and thus allow the use of close clearances without running the risk of causing the pump to bind while pumping a mixture of solid particles immersed in a liquid,

While in accordance with the Patent Statutes a preferred embodiment of the present invention has been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

What I claim is:

A nonclogging centrifugal pump for pumping a mixture of solid particles immersive in a fluid, said pump comprising a casing having a central intake side and a peripherally discharge, an impeller within said pump casing having axially spaced front nad rear shrouds, said front shroud having a central intake opening therein communicating with the central intake of the pump casing, a wear ring encircling the central intake, said wear ring having a surface disposed in a plane normal to the axis of the impeller, said surface having radially extending grooves therein of narrow width, said front shroud having an end surface terminating in a plane normal to the axis of the impeller in opposed relation with the said surface of said wear ring, and co-operating with said wear ring to define a pocket therebetween, said wear ring surface and said end surface of said impeller defining an annular open groove whereby pressure fluid from the discharge side of the impeller flows between the intake side of the casing and the front shroud directly through said annular groove to the central intake, said grooves in said wear ring constitute shearing surfaces that cooperate with the aforesaid end surface of the impeller to entrain solids in said pocket and reduce and guide the same into the central intake of the pump.

References Cited in the file of this patent UNITED STATES PATENTS 

